An Evaluation of a Rapid Real Time Polymerase Chain Reaction Assay for Detection of Group B Streptococcus as Part of a Neonatal Group B Streptococcus Prevention Strategy

Screening for infections in pregnancy - An overview of where we are today

Although most infections in pregnancy have very little impact, some affect either the mother or fetus or both. Screening must target those infections with consequences and furthermore, must be cost-beneficial. The introduction of any screening test for infections should take into consideration the prevalence of the condition, its consequences (health impact), the accuracy of the test and whether there are remedial steps including primary and secondary prevention to take with a positive or negative test. For some of these infections (for example syphilis and rubella) universal screening of all pregnant women has been the norm world-wide but as the epidemiology of these infections continue to change, a review of this practice must evolve. Furthermore, emerging infections line severe acute respiratory syndrome coronavirus-2 pose greater public health challenges. This article provides an overview of screening for infections in pregnancy, critically appraising screening for the common infections and arguing for abandoning of universal screening for rubella but advocating for universal screening for GBS and selective screening for CMV and toxoplasmosis.

Highly Sensitive and Rapid Identification of Streptococcus agalactiae Based on Multiple Cross Displacement Amplification Coupled With Lateral Flow Biosensor Assay

Streptococccus agalactiae (S. agalactiae) is an important neonatal pathogen that is associated with mortality and morbidity. Therefore, we developed a rapid, accurate, and sensitive method based on multiple cross displacement amplification (MCDA) for the detection of the target pathogen. Four sets of MCDA primers were designed for targeting the S. agalactiae-specific groEL gene, and one set of MCDA primers with the optimum amplification efficiency was screened for establishing the S. agalactiae-MCDA assay. As a result, the newly-developed assay could be conducted at a fixed temperature (61°C) for only 30 min, eliminating the use of complex instruments. A portable and user-friendly nanoparticle-based lateral flow biosensor (LFB) assay was employed for reporting MCDA results within 2 min. Our results suggested that the detection limit of the S. agalactiae-MCDA-LFB assay is 300 fg per reaction, and no cross-reaction occurred with non-S. agalactiae strains. For 260 vaginal and rectal swabs, the detection rate of the MCDA-LFB assay was 7.7%, which was in accordance with the reference method of enrichment/qPCR, and higher by 4.6% than the CHROMagar culture. Moreover, the total procedure time of the MCDA-LFB assay was around 50 min, including sample collection, template preparation, MCDA reaction, and result reporting. Therefore, the MCDA-LFB assay is superior to enrichment/qPCR and CHROMagar culture and has great promise for point-of-care testing of S. agalactiae from vaginal and rectal swabs of pregnant women in resource-limited settings.

No. 298-The Prevention of Early-Onset Neonatal Group B Streptococcal Disease

OBJECTIVE

To review the evidence in the literature and to provide recommendations on the management of pregnant women in labour for the prevention of early-onset neonatal group B streptococcal disease. The key revisions in this updated guideline include changed recommendations for regimens for antibiotic prophylaxis, susceptibility testing, and management of women with pre-labour rupture of membranes.

OUTCOMES

Maternal outcomes evaluated included exposure to antibiotics in pregnancy and labour and complications related to antibiotic use. Neonatal outcomes of rates of early-onset group B streptococcal infections are evaluated.

EVIDENCE

Published literature was retrieved through searches of MEDLINE, CINAHL, and The Cochrane Library from January 1980 to July 2012 using appropriate controlled vocabulary and key words (group B streptococcus, antibiotic therapy, infection, prevention). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to May 2013. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

The recommendations in this guideline are designed to help clinicians identify and manage pregnancies at risk for neonatal group B streptococcal disease to optimize maternal and perinatal outcomes. No cost-benefit analysis is provided.

SUMMARY STATEMENT

There is good evidence based on randomized control trial data that in women with pre-labour rupture of membranes at term who are colonized with group B streptococcus, rates of neonatal infection are reduced with induction of labour (I). There is no evidence to support safe neonatal outcomes with expectant management in this clinical situation.

RECOMMENDATIONS

The Accuracy of Group Beta Streptococcus Rectovaginal Cultures at 35 to 37 Weeks of Gestation in Predicting Colonization Intrapartum

Objective  This study aims to investigate accuracy of group beta Streptococcus (GBS) rectovaginal cultures at 35 to 37 weeks in predicting intrapartum colonization. Study Design  Institutional review board (IRB) approved prospective cohort study of 302 women from October 2015 to May 2017. Patients had the following tests for GBS: first trimester urine culture, rectovaginal culture at 35 to 37 weeks, and intrapartum rectovaginal culture. Outcomes included accuracy of 35- to 37-week GBS rectovaginal culture in detecting results intrapartum, and accuracy of first trimester urine culture in comparison to intrapartum rectovaginal cultures. Results  There was sufficient evidence of agreement between results at 35 to 37 weeks with intrapartum cultures ( p  = 0.001). However, agreement was weak, 11 patients (3.7%) were GBS positive intrapartum but negative at 35 to 37 weeks; and 33 patients (11%) were initially GBS positive but were negative intrapartum. Sensitivity and specificity of the 35- to 37-week culture was 69% (95% confidence interval [CI]:54-84%) and 87% (95% CI: 83-91%), respectively. There was also weak agreement between first trimester urine culture and intrapartum rectovaginal culture. Specificity for this assessment was 98% (95% CI: 97-100%) and was significantly different compared with antepartum GBS culture ( p  < 0.001). Accuracy between antepartum GBS rectovaginal culture and urine culture was similar (85 vs. 87%, p  = 0.47). Conclusion  The 35- to 37-week GBS rectovaginal culture might be a poor predictor for intrapartum colonization.

Comparison of BD MAX GBS and GenomEra GBS assays for rapid intrapartum PCR detection of vaginal carriage of group B streptococci

Objective

To compare the diagnostic performance of BD MAX and GenomEra PCR assays for a rapid PCR detection of vaginal carriage of group B streptococci at delivery.

Methods

This is a retrospective laboratory analysis of vaginal swab samples taken intrapartum from a randomly selected cohort of pregnant women giving birth at a single childbirth and maternity unit.

Results

Ninety-one culture-positive and 279 culture-negative vaginal samples were included from a cohort of 902 women. One-hundred-and-two specimens were found positive with the BD MAX and 84 with the GenomEra PCR assay. No statistically significant difference was observed compared to culture, sensitivity of BD MAX 84.6% (77/91) [95%CI 75.5–91.3] and of GenomEra 71.4% (65/91) [95%CI 61.0–80.4]. When compared to a combined reference standard, no statistically significant differences were seen between culture, BD MAX and GenomEra PCR assays. The sensitivities were 82.7% (91/110) [95%CI 74.3–89.3], 87.3% (96/110) [95%CI 79.6–92.9], and 79.1% (87/110) [95%CI 70.3–86.3], respectively.

Conclusion

Both PCR assays performed comparably to culture of the intrapartum vaginal samples. In particular, the GenomEra assay is potentially an easy and rapid on-site PCR test for intrapartum detection of vaginal carriage of group B streptococci at a maternity ward to identify women who should receive intrapartum antibiotic prophylaxis.

Group B Streptococcus Colonization in Late Pregnancy and Invasive Infection in Neonates in China: A Population-Based 3-Year Study

BACKGROUND

As no population-based studies of group B Streptococcus (GBS) colonization rates in late pregnancy (at 35-37 weeks of gestation) have been conducted in China, the incidence of and risk factors for neonatal early-onset GBS disease (GBS-EOD) in China remains poorly understood.

OBJECTIVES

To determine the GBS colonization rate in late pregnancy and neonatal GBS infection in Xiamen, China, and to assess the effectiveness of intrapartum antibiotic prophylaxis (IAP) for the prevention of neonatal GBS-EOD.

METHODS

A total of 49,908 pregnant women were enrolled between April 1, 2014 and March 31, 2017. Bacterial culture was used to diagnose GBS infection in both pregnant women and neonates. Women with GBS colonization received IAP during parturition or rupture of fetal membranes.

RESULTS

The GBS colonization rate was 13.89% (6,933/49,908); 50,772 neonates were born to 49,908 pregnant women, of whom 75 (1.48 per 1,000) were diagnosed with GBS-EOD. The incidence of GBS-EOD among neonates born to GBS-positive mothers (8.77‰; 62/7,068) was 29 times higher than that of neonates born to GBS-negative mothers (0.30‰; 13/43,704). Logistic regression analysis indicated that gestational bacteriuria, GBS disease in infants from previous pregnancies, and chorioamnionitis were risk factors for GBS-EOD (p = 0.007, p = 0.000, and p = 0.018, respectively). IAP effectively protected against neonatal GBS-EOD (p = 0.011).

CONCLUSIONS

GBS colonization was detected in nearly 14% of late pregnant women. The IAP for reducing GBS-EOD was effective. Therefore, universal screening of maternal GBS and subsequent IAP for those with GBS colonization should be implemented in China.

Assessment of conventional PCR and real-time PCR compared to the gold standard method for screening Streptococcus agalactiae in pregnant women

Group B Streptococcus is a causative agent of invasive neonatal infections. Maternal colonization by Streptococcus agalactiae is a necessary condition for vertical transmission, with efficient screening of pregnant women playing an essential role in the prevention of neonatal infections. In this study, we aimed to compare the performance of conventional polymerase chain reaction and real-time PCR assays as screening methods for S. agalactiae in pregnant women against the microbiological culture method considered as the gold-standard. A total of 130 samples from pregnant women were analyzed for sensitivity, specificity, positive predictive value, and negative predictive value. Statistical analysis was performed using the SPSS software, version 20.0. The verified colonization rate was 3.8% with the gold-standard, 17.7% with conventional PCR assay, and 29.2% with the real-time PCR test. The trials with conventional PCR and real-time PCR had a sensitivity of 100% and a specificity of 85.6% and 73.6%, respectively. The real-time PCR assay had a better performance compared to the gold-standard and a greater detection rate of colonization by S. agalactiae compared to conventional PCR assay. With its quick results, it would be suitable for using in routine screenings, contributing to the optimization of preventive approaches to neonatal S. agalactiae infection.

Diagnostic yield of real-time polymerase chain reaction in the diagnosis of intrapartum maternal rectovaginal colonization by group B Streptococcus: a systematic review with meta-analysis

Group B Streptococcus is the leading etiologic factor of neonatal sepsis. Intrapartum real-time polymerase chain reaction (RT-PCR) may allow faster and more accurate detection of maternal colonization. The aim of this study was to determine the sensitivity and specificity of RT-PCR when compared to the reference standard culture in selective broth media collected from rectovaginal tract from laboring women. We selected 15 studies that included 6368 women. Papers selection, data extraction, and quality assessment were carried out by two independent researchers. The prevalence of maternal colonization was 23.8% by RT-PCR and 22.1% by culture. The meta-analysis demonstrated an RT-PCR sensitivity of 93.7% (CI 92.1-95.3), and specificity of 97.6% (CI 97.0-98.1). This result is above the cutoff point defined by the Centers for Disease Control and Prevention for clinical usefulness. In conclusion, RT-PCR for GBS screening in labor ward is a promising tool; however, further well-designed studies to justify its use are needed.

Intrapartum PCR assay versus antepartum culture for assessment of vaginal carriage of group B streptococci in a Danish cohort at birth

The aim of this study was to compare the performances of two strategies for predicting intrapartum vaginal carriage of group B streptococci (GBS). One strategy was based on an antepartum culture and the other on an intrapartum polymerase chain reaction (PCR). We conducted a prospective observational study enrolling 902 pregnant women offered GBS screening before delivery by two strategies. The Culture-strategy was based on vaginal and rectal cultures at 35–37 weeks’ gestation, whereas the PCR-strategy was based on PCR assay on intrapartum vaginal swab samples. An intrapartum vaginal culture for GBS was used as the reference standard from which the performances of the 2 strategies were evaluated. The reference standard showed a GBS-prevalence of 12%. The culture-strategy performed with a sensitivity of 82%, specificity of 91%, positive predictive value (PPV) of 55%, negative predictive value (NPV) of 98%, and Likelihood ratio (LH+) of 9.2. The PCR-strategy showed corresponding values as sensitivity of 83%, specificity of 97%, PPV of 78%, NPV of 98%, and LH+ of 27.5. We conclude that in a Danish population with a low rate of early-onset neonatal infection with GBS, the intrapartum PCR assay performs better than the antepartum culture for identification of GBS vaginal carriers during labor.

Prévention de l'infection néonatale à streptocoques du groupe B d'apparition précoce

OBJECTIF

Analyser les données issues de la littérature et formuler des recommandations sur la prise en charge des parturientes en vue de prévenir l'infection néonatale à streptocoques du groupe B d'apparition précoce. Parmi les révisions clés que renferme la présente directive clinique mise à jour, on trouve des modifications quant aux recommandations en ce qui concerne les schémas posologiques d'antibioprophylaxie, les épreuves de sensibilité et la prise en charge des femmes présentant une rupture prématurée des membranes.

ISSUES

Parmi les issues maternelles évaluées, on trouvait l'exposition aux antibiotiques au cours de la grossesse et du travail, ainsi que les complications associées à l'administration d'antibiotiques. Les issues néonatales associées aux taux d'infection néonatale à streptocoques du groupe B d'apparition précoce ont été évaluées. RéSULTATS: La littérature publiée a été récupérée par l'intermédiaire de recherches menées dans PubMed, CINAHL et The Cochrane Library entre janvier 1980 et juillet 2012, au moyen d'un vocabulaire contrôlé et de mots clés appropriés (« group B streptococcus », « antibiotic therapy », « infection », « prevention »). Les résultats ont été restreints aux analyses systématiques, aux essais comparatifs randomisés / essais cliniques comparatifs et aux études observationnelles. Aucune restriction n'a été appliquée en matière de date ou de langue. Les recherches ont été mises à jour de façon régulière et intégrées à la directive clinique jusqu'en mai 2013. La littérature grise (non publiée) a été identifiée par l'intermédiaire de recherches menées dans les sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, dans des registres d'essais cliniques et auprès de sociétés de spécialité médicale nationales et internationales.

VALEURS

La qualité des résultats est évaluée au moyen des critères décrits dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs (Tableau 1). AVANTAGES, DéSAVANTAGES ET COûTS: Les recommandations que renferme la présente directive clinique sont conçues de façon à aider les cliniciens à identifier et à assurer la prise en charge des grossesses exposées à un risque d'infection néonatale à streptocoques du groupe B, en vue d'optimiser les issues maternelles et périnatales. Aucune analyse de rentabilité n'est fournie. DéCLARATION SOMMAIRE: Nous disposons de bonnes données (issues d'essais comparatifs randomisés) indiquant que, chez les femmes présentant une rupture prématurée des membranes à terme qui sont colonisées par des streptocoques du groupe B, le déclenchement du travail entraîne une baisse des taux d'infection néonatale. (I) Aucune donnée ne permet de soutenir que, dans une telle situation clinique, la prise en charge non interventionniste permet l'obtention de bonnes issues néonatales. RECOMMANDATIONS.

The Prevention of Early-Onset Neonatal Group B Streptococcal Disease

OBJECTIVE

To review the evidence in the literature and to provide recommendations on the management of pregnant women in labour for the prevention of early-onset neonatal group B streptococcal disease. The key revisions in this updated guideline include changed recommendations for regimens for antibiotic prophylaxis, susceptibility testing, and management of women with pre-labour rupture of membranes.

OUTCOMES

Maternal outcomes evaluated included exposure to antibiotics in pregnancy and labour and complications related to antibiotic use. Neonatal outcomes of rates of early-onset group B streptococcal infections are evaluated.

EVIDENCE

Published literature was retrieved through searches of MEDLINE, CINAHL, and The Cochrane Library from January 1980 to July 2012 using appropriate controlled vocabulary and key words (group B streptococcus, antibiotic therapy, infection, prevention). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to May 2013. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

The recommendations in this guideline are designed to help clinicians identify and manage pregnancies at risk for neonatal group B streptococcal disease to optimize maternal and perinatal outcomes. No cost-benefit analysis is provided.

SUMMARY STATEMENT

There is good evidence based on randomized control trial data that in women with pre-labour rupture of membranes at term who are colonized with group B streptococcus, rates of neonatal infection are reduced with induction of labour (I). There is no evidence to support safe neonatal outcomes with expectant management in this clinical situation.

RECOMMENDATIONS

Group B Streptococci Screening Before Repeat Cesarean Delivery: A Cost-Effectiveness Analysis

OBJECTIVE

To estimate the cost-effectiveness of universal group B streptococci (GBS) screening in women with a singleton pregnancy planning a repeat cesarean delivery.

METHODS

We conducted a decision analysis from a health care perspective to compare the cost-effectiveness of GBS screening for women planning a repeat cesarean delivery. With universal screening, all GBS-positive women who labored before a scheduled cesarean delivery received antibiotic prophylaxis. With no screening, women who presented in labor received antibiotics based on risk-based criteria. Neonates born to women colonized with GBS were at risk for early-onset GBS disease, disability, and death. We assumed a GBS prevalence of 25%, that 26.6% of women labored between 35 weeks of gestation and their scheduled time for cesarean delivery, and that 3.3% who planned a repeat cesarean delivery instead delivered vaginally. The primary outcome was cost per neonatal quality-adjusted life-year gained, with a cost-effectiveness threshold of $100,000 per quality-adjusted life-year. Neonatal quality of life was assessed using five health states (healthy, mild, moderate, or severe disability, and death) with a life expectancy of 79 years for healthy neonates. One-way sensitivity and Monte Carlo analyses were used to evaluate the results.

RESULTS

In the base case, universal GBS screening in women planning a repeat cesarean delivery was not cost-effective compared with no screening, costing $114,445 per neonatal quality-adjusted life-year gained. The cost to prevent an adverse outcome from GBS exceeded $400,000. If greater than 28% of women were GBS-positive, greater than 29% labored before their scheduled delivery, or greater than 10% delivered vaginally, universal screening became cost effective.

CONCLUSION

Universal GBS screening in women with a singleton pregnancy planning a repeat cesarean delivery may not be cost-effective in all populations. However, in populations with a high GBS prevalence, women at high risk of laboring before their scheduled cesarean delivery, or women who may ultimately opt for a vaginal delivery, GBS screening may be cost effective.

Accuracy of a rapid real-time polymerase chain reaction assay for diagnosis of group B Streptococcus colonization in a cohort of HIV-infected pregnant women

OBJECTIVE

There are limited data regarding Xpert performance to detect Group B Streptococcus (GBS) in HIV-infected pregnant women. We evaluated the accuracy of a rapid real-time polymerase chain reaction (PCR) test in a cohort of HIV-infected women.

METHODS

At 35-37 weeks of pregnancy, a pair of combined rectovaginal swabs were collected for two GBS assays in a cohort of sequentially included HIV-infected women in Rio de Janeiro: (1) culture; and (2) real-time PCR assay [GeneXpert GBS (Cepheid, Sunnyvale, CA)]. Using culture as the reference, sensitivity, specificity, positive and negative-likelihood ratios were estimated.

RESULTS

From June 2012 to February 2015, 337 pregnant women met inclusion criteria. One woman was later excluded, due to failure to obtain a result in the index test; 336 were included in the analyses. The GBS colonization rate was 19.04%. Sensitivity and specificity of the GeneXpert GBS assay were 85.94% (95% CI: 75.38-92.42) and 94.85% (95% CI: 91.55-96.91), respectively. Positive and negative predictive values were 79.71% (95% CI: 68.78-87.51) and 96.63% (95% CI: 93.72-98.22), respectively.

CONCLUSIONS

GeneXpert GBS is an acceptable test for the identification of GBS colonization in HIV-infected pregnant women and represents a reasonable option to detect GBS colonization in settings where culture is not feasible.

Ongoing Cases of Early-Onset Group B Streptococcal Disease in the Era of Screening and Prophylaxis

OBJECTIVE

We reviewed cases of group B Streptococcus (GBS) sepsis in term infants at our institution to identify areas for potential prevention.

METHODS

We identified cases by searching our institution's microbiology databases for all positive GBS blood and cerebrospinal fluid cultures taken from infants between 2008 and 2013. Patients were included if the timing of the positive culture met the criteria for early-onset GBS disease (age 7 days or under). Charts that met inclusion criteria were abstracted for details related to antepartum screening, intrapartum care, and postpartum outcome.

RESULTS

There are an average of 10 000 deliveries per year in our institution. During the five-year period (2008-2013), we identified 13 cases representing early-onset GBS disease in term infants. Of the 13 cases, nine mothers screened negative for GBS, two screened positive, and two were screened unknown. Four cases qualified for intrapartum prophylaxis; of these, two did not receive appropriate prophylaxis, one because of parental refusal and one for unspecified reasons after the membranes had been ruptured for > 18 hours. All 13 infants had confirmed GBS bacteremia, and four had concurrent GBS meningitis. One infant died and one infant had neurologic sequelae.

CONCLUSION

Early-onset GBS disease in term infants continues to occur at our institution, and consequences for the infant can be severe. The majority of cases identified were screened and managed in accordance with current guidelines. Most cases were GBS negative when screened in the antepartum period, raising the question of whether a more sensitive test or a test closer to delivery could prevent further cases of early-onset GBS disease.

Diagnosis and management of group B streptococcus in pregnancy

Group B streptococcus (GBS) can cause significant maternal and neonatal morbidity. Over the past 30 years, reductions in early-onset GBS neonatal sepsis in the United States have been attributable to the guidelines from the Centers for Disease Control and Prevention for antepartum screening and treating this organism during labor. This article highlights the clinical implications, screening, diagnosis, prophylactic interventions, and future therapies for mothers with GBS during the peripartum period.

Intrapartum GBS screening and antibiotic prophylaxis: a European consensus conference

Group B streptococcus (GBS) remains worldwide a leading cause of severe neonatal disease. Since the end of the 1990s, various strategies for prevention of the early onset neonatal disease have been implemented and have evolved. When a universal antenatal GBS screening-based strategy is used to identify women who are given an intrapartum antimicrobial prophylaxis, a substantial reduction of incidence up to 80% has been reported in the USA as in other countries including European countries. However recommendations are still a matter of debate due to challenges and controversies on how best to identify candidates for prophylaxis and to drawbacks of intrapartum administration of antibiotics. In Europe, some countries recommend either antenatal GBS screening or risk-based strategies, or any combination, and others do not have national or any other kind of guidelines for prevention of GBS perinatal disease. Furthermore, accurate population-based data of incidence of GBS neonatal disease are not available in some countries and hamper good effectiveness evaluation of prevention strategies. To facilitate a consensus towards European guidelines for the management of pregnant women in labor and during pregnancy for the prevention of GBS perinatal disease, a conference was organized in 2013 with a group of experts in neonatology, gynecology-obstetrics and clinical microbiology coming from European representative countries. The group reviewed available data, identified areas where results were suboptimal, where revised procedures and new technologies could improve current practices for prevention of perinatal GBS disease. The key decision issued after the conference is to recommend intrapartum antimicrobial prophylaxis based on a universal intrapartum GBS screening strategy using a rapid real time testing.

Molecular-based screening for perinatal group B streptococcal infection: implications for prevention and therapy

Group B streptococci (GBS) are a leading cause of infectious neonatal morbidity and mortality. Timely and accurate identification of colonized pregnant women is imperative to implement intrapartum antibioprophylaxis (IAP) to reduce the risk of early neonatal sepsis. Current guidelines recommend screening for GBS carriage with vaginal-rectal cultures. However, cultures require 24-72 h, thus precluding their use for intrapartum screening and these are only performed at 35-37 weeks gestation. New rapid molecular-based tests can detect GBS within hours. They have the potential to be used intrapartum and to allow for selective IAP in women carrying GBS. An advantage is that they can sometimes be performed by non-laboratory staff in the labor suite, thus avoiding delays in sample transfers to the microbiology laboratory. Another possible use of molecular-based assays is for the diagnosis of neonatal sepsis, where tests with a short turnaround time and high sensitivity and specificity are crucial. In this situation, the detection of microorganisms once antibiotic therapy has already been started is important, as treatment is started immediately once sepsis is suspected without waiting for microbiological confirmation. In this article, we discuss the state-of-the-art molecular-based tests available for GBS screening during pregnancy, as well as their implications for IAP for the diagnosis and prevention of neonatal sepsis.

The prevention of early-onset neonatal group B streptococcal disease

OBJECTIVE

To review the evidence in the literature and to provide recommendations on the management of pregnant women in labour for the prevention of early-onset neonatal group B streptococcal disease. The key revisions in this updated guideline include changed recommendations for regimens for antibiotic prophylaxis, susceptibility testing, and management of women with pre-labour rupture of membranes.

OUTCOMES

Maternal outcomes evaluated included exposure to antibiotics in pregnancy and labour and complications related to antibiotic use. Neonatal outcomes of rates of early-onset group B streptococcal infections are evaluated.

EVIDENCE

Published literature was retrieved through searches of MEDLINE, CINAHL, and The Cochrane Library from January 1980 to July 2012 using appropriate controlled vocabulary and key words (group B streptococcus, antibiotic therapy, infection, prevention). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to May 2013. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1).

BENEFITS, HARMS, AND COSTS

The recommendations in this guideline are designed to help clinicians identify and manage pregnancies at risk for neonatal group B streptococcal disease to optimize maternal and perinatal outcomes. No cost-benefit analysis is provided.

SUMMARY STATEMENT

There is good evidence based on randomized control trial data that in women with pre-labour rupture of membranes at term who are colonized with group B streptococcus, rates of neonatal infection are reduced with induction of labour. (I) There is no evidence to support safe neonatal outcomes with expectant management in this clinical situation.

RECOMMENDATIONS

1. Offer all women screening for colonization with group B streptococcus at 35 to 37 weeks' gestation with culture taken from one swab first to the vagina and then to the rectum (through the anal sphincter). (II-1A) This includes women with planned Caesarean delivery because of their risk of labour or ruptured membranes earlier than the scheduled Caesarean delivery. (II-2B) 2. Because of the association of heavy colonization with early onset neonatal disease, provide intravenous antibiotic prophylaxis for group B streptococcus at the onset of labour or rupture of the membranes to: • any woman positive for group B streptococcus by vaginal/rectal swab culture screening done at 35 to 37 weeks' gestation (II-2B); • any woman with an infant previously infected with group B streptococcus (II-3B); • any woman with documented group B streptococcus bacteriuria (regardless of level of colony-forming units) in the current pregnancy. (II-2A) 3. Manage all women who are < 37 weeks' gestation and in labour or with rupture of membranes with intravenous group B streptococcus antibiotic prophylaxis for a minimum of 48 hours, unless there has been a negative vaginal/rectal swab culture or rapid nucleic acid-based test within the previous 5 weeks. (II-3A) 4. Treat all women with intrapartum fever and signs of chorioamnionitis with broad spectrum intravenous antibiotics targeting chorioamnionitis and including coverage for group B streptococcus, regardless of group B streptococcus status and gestational age. (II-2A) 5. Request antibiotic susceptibility testing on group B streptococcus-positive urine and vaginal/rectal swab cultures in women who are thought to have a significant risk of anaphylaxis from penicillin. (II-1A) 6. If a woman with pre-labour rupture of membranes at ≥ 37 weeks' gestation is positive for group B streptococcus by vaginal/rectal swab culture screening, has had group B streptococcus bacteriuria in the current pregnancy, or has had an infant previously affected by group B streptococcus disease, administer intravenous group B streptococcus antibiotic prophylaxis. Immediate obstetrical delivery (such as induction of labour) is indicated, as described in the Induction of Labour guideline published by the Society of Obstetricians and Gynaecologist in September 2013. (II-2B) 7. At ≥ 37 weeks' gestation, if group B streptococcus colonization status is unknown and the 35- to 37-week culture was not performed or the result is unavailable and the membranes have been ruptured for greater than 18 hours, administer intravenous group B streptococcus antibiotic prophylaxis. (II-2B) 8. If a woman with pre-labour rupture of membranes at < 37 weeks' gestation has an unknown or positive group B streptococcus culture status, administer intravenous group B streptococcus prophylaxis for 48 hours, as well as other antibiotics if indicated, while awaiting spontaneous or obstetrically indicated labour. (II-3B).

How can the microbiologist help in diagnosing neonatal sepsis?

Neonatal sepsis can be classified into two subtypes depending upon whether the onset of symptoms is before 72 hours of life (early-onset neonatal sepsis—EONS) or later (late-onset neonatal sepsis—LONS). These definitions have contributed greatly to diagnosis and treatment by identifying which microorganisms are likely to be responsible for sepsis during these periods and the expected outcomes of infection. This paper focuses on the tools that microbiologist can offer to diagnose and eventually prevent neonatal sepsis. Here, we discuss the advantages and limitation of the blood culture, the actual gold standard for sepsis diagnosis. In addition, we examine the utility of molecular techniques in the diagnosis and management of neonatal sepsis.

Assessment of intrapartum antibiotic prophylaxis for the prevention of early-onset group B Streptococcal disease

BACKGROUND

Most early-onset group B streptococcal (GBS) disease in recent years has occurred in newborns of prenatally GBS-negative mothers who missed intrapartum antibiotic prophylaxis (IAP). We aimed to assess the accuracy of prenatal culture in predicting GBS carriage during labor, the IAP use, and occurrence of early-onset GBS disease.

METHODS

We obtained vaginal-rectal swabs at labor for GBS culture from 5497 women of ≥ 32 weeks' gestation and surface cultures at birth from newborns between February 5, 2008 and February 4, 2009 at 3 hospitals in Houston, TX and Oakland, CA. Prenatal cultures were performed by a healthcare provider during routine care, and culture results were obtained from medical records. The accuracy of prenatal culture in predicting intrapartum GBS carriage was assessed by positive and negative predictive values. Mother-to-newborn transmission of GBS was assessed. Newborns were monitored for early-onset GBS disease.

RESULTS

GBS carriage was 24.5% by prenatal and 18.8% by labor cultures. Comparing prenatal with labor GBS cultures of 4696 women, the positive predictive value was 50.5% and negative predictive value was 91.7%. IAP, administered to 93.3% of prenatally GBS-positive women, was 83.7% effective in preventing newborn's GBS colonization. Mother-to-newborn transmission of GBS occurred in 2.6% of elective cesarean deliveries. Two newborns developed early-onset GBS disease (0.36/1000 births); the prenatal GBS culture of one was negative, the other's was unknown.

CONCLUSIONS

IAP was effective in interrupting mother-to-newborn transmission of GBS. However, approximately 10% of prenatally GBS-negative women were positive during labor and missed IAP, whereas approximately 50% of prenatally GBS-positive women were negative during labor and received IAP. These findings emphasize the need for rapid diagnostics during labor.

Prevention of Group B Streptococcus early-onset disease: a toolkit by the California Perinatal Quality Care Collaborative

The California Perinatal Quality Care Collaborative (CPQCC) was organized in 1996 in an effort to improve perinatal outcomes in California. CPQCC has a robust infrastructure of quality improvement resources and expertise and uses a database of demographic and outcome data from neonatal intensive care units in California. In 2004, CPQCC developed a toolkit to provide an evidence-based framework and supporting documents for hospitals to use in systematically addressing persistent early-onset disease (EOD) because of Group B Streptococcus (GBS) in their centers. The CPQCC toolkit was based on the 2002 Centers for Disease Control guideline, 'Prevention of Perinatal Group B Streptococcal Disease.' This article presents an updated version of the CPQCC toolkit reflecting several population studies published since the 2002 guideline. Current epidemiological trends in incidence of EOD with GBS, changes in antibiotic sensitivity and the potential value of newer strategies are discussed.